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My 06 g6 that has sat for a bit has some issues i need help resolving

2K views 8 replies 5 participants last post by  EDjarvis42 
#1 ·
My 2006 Pontiac g6 SE 2.4l that I'm buying from a buddy of mine and it has almost 98k miles on it and when you turn the key the guages in the cluster swing which I think is normal because of the sensors checking the systems in the car but I look at my odometer and it says 0 miles at first but after about 3 seconds of having the key in the run position it goes on to say error but when I had the spare key (non transponder) it read 98k but sometimes said error. When I go to start the car though besides a bad battery the car cranks right up but runs really rich. I ran through a quarter tank of gas just by letting it idle for 20 mins. And it only gets about 11mpg. But I can't read any codes from the check engine light because the obd2 port isn't getting any power and I checked all fuses and cleanliness of the port. And my speed sensor went out on the car and the car wont shift and when i throw it in reverse my reverse lights won't kick on. Can someone help me out with making me 100% positive that it's just my pcm and speed sensor that's bad?
 
#2 ·
You seem to indicate that you have not purchased the car yet. You may want to consider if it is is your best interests to do so with so many issues and limited options for diagnosis (no OBD2). Only you can decide if it is a good enough deal to warrant the risk. That said, at a wild guess I would double check the connection to the engine management unit simply due to the wide range of odd issues. You also may want to check the ground wiring. Both have been associated with weird electrical issues. Hope you get a good outcome.
 
#4 ·
Sounds like a lousy BCM connector with your getting occasional errors. Could be a mouse through the harness too, one is easy, one isn't.

If the G6 is anything like every other GM car, check the lighter sockets for coins and check the fuse. Offer your buddy 200 bucks for the car, he's not getting any more than that from anyone else.

Oh! and these cars are super weird, like if you take a taillight out the car won't charge and things like that, so if everything looks right on something that's reporting as bad, look elsewhere.
 
#5 ·
Yea everything looks fine I just think personally that the speed sensor is causing the reverse lights not to come on when it's in reverse but I will defiantly try to clean the wiring harnesses to the ECU with an old toothbrush and some rubbing alcohol to see if that resolves my issue. And yea the cars base price is 200 its complicated my friend said the cars mine but I have to pay 200 for the title plus what its gonna cost to have the title signed into my name.
 
#6 ·
Speed sensor isn't part of the reverse circuit. I'm almost positive.

Rework the BCM connector, not the ECU for the odometer issue. You're having communications issues.

If you get desperate you can power the your OBD reader from elsewhere and likely still pull data. You have a check engine light, right? If you're dumping fuel it's probably like a coolant temp sensor.

Hey for 200 bucks for the title work, if it doesn't work out, sell some parts off of it and have it hauled away. You'll make that back.
 
#7 ·
I thought about that because that car is profitable as is right now the scrap yard will give me 500 for it so I can make a 300 dollar profit but I might roadkill it and say I don't need reverse lights and what not. Just so long as my break lights work and my headlights work which they do but I need to figure out if it is just my ECU that needs reprogramming or if it's just a loose or dirty wiring harness because if the ECU goes bad i would assume that 9 times out of 10 the car wouldn't fire or crank but I know the transmission needs service with a fluid change and if anything I'll hit that motor and cram a small block v8 in it and make it like a hotrod garage protect because the nose of that car is big enough to do that I just need to replace the rear axle with a rear wheel drive type of deal. Only reason why I want this thing to run properly is because one its never been loved on and taken care of and 2 I want a g8 and this is the closest thing I can get to one that actually looks really stylish with the aftermarket projector headlights and headlight frames. If I could post pics or vids on here I would show visually what's happening so it would maybe get me a pinpointed trouble shoot and solution
 
#9 ·
Sounds like the fuel pump is pushing too much gas from sitting. 2.4l ecotecs notoriously run rich or lean from a malfunctioning pump. Just dealt with this on a 07 2.4l ecotec hhr running too lean and only got 11-15 mpg average. Replaced pump and jumped up to 24mpg average. Also a failed speed sensor can cause all sorts of problems on auto transmissions including limited gear operations, hard shifts, and or delayed shifts. As for the obd port not working check the fuse labeled HVAC CTRL BATT located under the dash on passenger side.
 
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